Conventionally, sheet processing apparatuses have been put into practice that are provided with a cutting section that cuts the edges of a sheet stack and aligns the edges of a sheet stack that has been center folded.
In recent years, sheet processing apparatuses are being provided that have a cutting section, receive sheets on which images have been formed by an image forming apparatus such as a copying machine, printer, etc., carry out center stapling and center folding, and after binding a bound book like a weekly magazine, cut and align the edges of the sheet stack using the cutting section.
In the Unexamined Japanese Patent Application Publication No. 2005-306559, a sheet processing apparatus is disclosed in which a sheet stack prepared by center stapling and center folding is conveyed, the sheet stack is made to press against a stopper to correct skews in the sheet stack, and then the front edge of the sheet stack is cut by a cutting section.
In the sheet processing apparatus of the Unexamined Japanese Patent Application Publication No. 2005-306559, after correcting skews of the sheet stack, by applying pressure to it in the thickness direction the sheet stack is restricted its orientation and shaped, and then the sheet stack is cut.
However, in the orientation restriction and shaping process as in the Unexamined Japanese Patent Application Publication No. 2005-306559, if there are curls in the sheets, there was the problem that the sheet stack may not be shaped sufficiently and the edge of the sheet stack after cutting could not be finished to be flat sometimes.
In particular, in the shaping process of pressing the sheet stack, it became clear that sometimes it is not possible to remove the twisting of the sheet stack and therefore the quality of a booklet made from the sheet stack was reduced.
Further, regarding the problem, detailed explanations are given in the explanations of the preferred embodiments of the present invention.
One aspect of the present invention is a sheet processing apparatus comprising:
a sheet supporting table which supports a sheet stack made of a plurality of sheets which have been folded;
a stopper against which a first edge of the sheet stack which is a side to be cut of the sheet stack is pressed on the sheet supporting table; and
a pushing member which pushes a second edge of the sheet stack which is a side of a folded part of the sheet stack so that the first edge of the sheet stack is pressed against the stopper,
wherein the pushing member comprises a first surface which is inclined with respect to a sheet supporting surface of the sheet supporting table so that the first surface restricts a height of the folded part of the sheet stack with respect to the sheet supporting surface when the pushing member presses the sheet stack towards the stopper.
In addition, an image forming system comprising:
an image forming apparatus which forms an image onto a sheet; and
the above-mentioned sheet processing apparatus which performs a finishing process to the sheet onto which the image has been formed by the image forming apparatus.